Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 232133
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
333 PM CST FRI JAN 23 2015

.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 333 PM CST FRI JAN 23 2015

GENERALLY QUIET SHORT TERM PERIOD...WITH THE WEEKEND SNOW EVENT
MAINLY OCCURRING IN THE LONG RANGE PERIOD.

AS THE TROUGH AXIS PUSHED THROUGH TODAY...DRIER MID AND LOW LEVEL
FLOW CLEARED SKIES ACROSS THE ENTIRE FA.  NEAR ST. CLOUD AND AREAS
NORTH...TEMPERATURES SHOT UP INTO THE LOW AND MID 40S THANKS TO THE
SUN AND SNOW-FREE GROUND. A VISIBLE SATELLITE LOOP SHOWS RAPID
MELTING OF THE SNOW PACK...ESPECIALLY ACROSS WESTERN MN...AND DEW
POINTS HAVE INCREASED INTO THE LOW 30S.

A STRATUS DECK IS SINKING SOUTHEAST THROUGH NORTHERN MN...BUT THE HI-
RES GUIDANCE IS BACKING OFF ON HOW FAR WEST THE CLOUD COVER WILL
EXTEND ONCE IT ARRIVES. MUCH OF WESTERN MN SHOULD REMAIN CLEAR
THROUGH THE EVENING.  MODEL SOUNDINGS DO INDICATE BLOSSOMING LOW
LEVEL CLOUDINESS OVERNIGHT HOWEVER AS TEMPERATURES COOL AND AMPLE
MOISTURE BECOMES TRAPPED IN THE BOUNDARY LAYER.

THERE REMAINS DIFFERENCES IN THE TIMING OF THE CLIPPER APPROACHING
THE AREA TOMORROW...BUT THE ECMWF DOES SPREAD LIGHT PRECIPITATION
INTO WESTERN MINNESOTA BY LATE AFTERNOON...SO STUCK WITH SOME SLIGHT
CHANCE TO CHANCE POPS THERE PRIOR TO 6PM SATURDAY.  LOW LEVEL
TEMPERATURES WILL BE WARM HOWEVER...SO ANY LIGHT PRECIP THAT DOES
REACH WESTERN MN BY THIS TIME WILL LIKELY BE A WINTRY MIX...BUT WILL
NOT TAKE LONG TO CHANGE TO SNOW.


.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 333 PM CST FRI JAN 23 2015

LIKE THE PENDULUM OF A CLOCK...THE MODELS CONTINUE MOVING BACK
AND FORTH ON THE TRACK OF THE HEAVIEST QPF WITH THE CLIPPER
DROPPING IN SATURDAY NIGHT. YESTERDAY IT WAS OFF THE EAST AND NOW
TODAY ITS BACK TO THE WEST. ITS TIED TO SHORT WAVES MOVING THROUGH
THE UPPER TROUGH OVER QUEBEC...WITH A DEEPER TROUGH PUSHING THE
CLIPPER BACK TO THE WEST. CONFIDENCE IS HIGH THAT IT WILL SNOW
ACROSS ALL OF OUR FA SATURDAY NIGHT...BUT THERE REMAINS QUITE A
BIT OF SPREAD IN THE TRACK OF THE HEAVIEST QPF. THE GFS WAS
FARTHEST WEST TODAY EXTENDING FROM CENTRAL ND THROUGH SW MN AND NW
IA. THE ECMWF IS ON A DIAGONAL FROM NW TO SE MN WHILE THE 12Z NAM
STRETCHED FROM NORTH CENTRAL MN THROUGH WESTERN WI. THE 18Z NAM
HAS ALREADY SHIFTED SOUTHWEST WITH THE AXIS FROM KAXN TO KRST. THE
WPC 24 HOUR PROBABILISTIC WINTER GUIDANCE...WHICH IS A 57 MEMBER
ENSEMBLE... FAVORS LIKELY PROBABILITIES FOR 2 OR MORE INCHES OF
SNOW ACROSS JUST ABOUT ALL OF CENTRAL AND SOUTHERN MN.
PROBABILITIES DROP OFF PRETTY QUICKLY HEADING EAST ACROSS WEST
CENTRAL WI. THERE ARE EVEN SOME LOW PROBABILITIES FOR 4 OR MORE
INCHES ACROSS THE METRO. HENCE...A FORECAST OF LIKELY TO
CATEGORICAL POPS IS IN PLACE FOR SATURDAY NIGHT WITH AROUND 2
INCHES OF ACCUMULATION IN THE AFOREMENTIONED AREAS. ONCE WE CAN
NAIL DOWN THE HEAVIER QPF TRACK...AN AREA OF 3 TO 4 INCHES WILL
LIKELY BE NEEDED.

THE SNOW WILL TAPER OFF QUICKLY ON SUNDAY...BUT ANOTHER CLIPPER
WILL COME OUR WAY FOR SUNDAY NIGHT AND MONDAY. THIS ONE CURRENTLY
HAS THE MOST SNOW OFF TO THE NORTH AND EAST OF THE METRO...BUT
THAT CAN CERTAINLY CHANGE. ONCE THIS FEATURE MOVES BY...UPPER
LEVEL RIDGING WILL SPREAD IN FROM THE ROCKIES... CONTINUING OUR
WELL ABOVE NORMAL TREND. HIGHS BY THE MIDDLE OF NEXT WEEK MAY BE
BACK TO LEVELS WE AREA SEEING THIS AFTERNOON...WHICH IS IN THE MIDDLE
30S TO MIDDLE 40S.

THERE IS SOME UNCERTAINTY TO THE STRENGTH OF A PACIFIC SYSTEM AS
IT MOVES THROUGH ON THURSDAY. THE GFS AND ECMWF ARE PRETTY
SIMILAR ON TIMING AND LOCATION...BUT NEITHER HAVE MUCH QPF.
BLENDED GUIDANCE RESULTED IN LOW CHANCE POPS ACROSS PARTS OF WEST
CENTRAL WI. THIS COULD END UP BEING A LIGHT WINTRY MIX DEPENDING
ON WHEN IT OCCURS. PLENTY OF TIME TO ADJUST WITH JUST LIGHT SNOW
MENTIONED NOW.

FINALLY...ANOTHER CLIPPER IS SHOWN BY BOTH THE GFS AND ECMWF TO
MOVE IN FRIDAY/FRIDAY NIGHT. AGAIN...TIMING AND LOCATION LOOK
GOOD. HIGH CHANCE POPS ALREADY IN PLACE FOR A GOOD PORTION OF THE
MN CWA BY FRIDAY NIGHT. IT CERTAINLY LOOKS COLDER FOR NEXT WEEKEND
AS THE FLOW ALOFT TURNS MORE NORTHERLY WITH A DEEPENING TROUGH
OVER THE EASTERN CONUS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1147 AM CST FRI JAN 23 2015

QUIET STARTING OUT THIS AFTERNOON WITH WIDESPREAD VFR CONDITIONS.
TROUGH AXIS ORIENTED SW TO NE THROUGH CENTRAL MN AT THIS TIME WILL
CONTINUE PUSHING SE THROUGH THE DAY. A SIMILARLY ORIENTED BAND OF
MID CLOUDS CONTINUES PUSHING SOUTHEAST AHEAD OF THE TROUGH AXIS.
LIGHT FREEZING RAIN HAD FALLEN OUT OF THESE CLOUDS THIS
MORNING...BUT LOW LEVEL DRYING CONTINUES PREVENTING MUCH OF
ANYTHING FROM REACHING THE GROUND. MOST OF THE CWA WILL SEE CLEAR
SKIES FOR MUCH OF THE AFTERNOON...BEFORE A SOLID DECK OF STRATUS
CURRENTLY IN NORTHERN MN MOVES INTO CENTRAL MN BY LATE AFTERNOON
AND PROGRESSES TOWARD THE IOWA BORDER THROUGH THE EVENING. LIGHTER
WINDS AND A MELTING SNOW PACK SUGGEST THE DECK EXPANDING AND
LOWERING OVERNIGHT...WITH SOME FOG A POSSIBILITY.

KMSP...LOW LEVEL DRYING HAS MADE FOR A MORE OPTIMISTIC FORECAST
THIS AFTERNOON...WITH CLEAR SKIES HOLDING TRUE UNTIL THE STRATUS
ABRUPTLY ARRIVES AROUND 5-6PM. CIGS WILL NOT GRADUALLY GO
DOWN...BUT INSTEAD WE`LL HAVE CLEAR SKIES SUDDENLY BECOME OVERCAST
WHEN THE STRATUS DECK ARRIVES.

/OUTLOOK FOR KMSP/
SATURDAY NIGHT...BECOMING MVFR. CHC IFR CIGS/VSBYS -SN MAINLY
AFTER 06Z SUN. 1-3" OF ACCUMULATION POSSIBLE. WIND W 5-10 KTS.
SUNDAY...MVFR WITH -SN/IFR POSSIBLE. WIND NW 10G20 KTS.
MONDAY...VFR. WIND SW 5-10 KTS.


&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&

$$

SHORT TERM...SPD
LONG TERM...RAH
AVIATION...SPD


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